How to Validate Date Input in JavaScript

A Date instance can be created in JavaScript by passing the date time string as the parameter in yyyy-mm-dd format as in Date(“2015-01-31”). There’s something important to note here though.

If you pass an invalid date string, the Date instance would still be created. For instance, “2015-02-30” is not a valid date but the Date instance would still be created. The date will however be adjust to point to the next logical date and in this case, our Date will be set as “2015-03-02”.

Thus you’ll have to verify the month, year and day of a Date separately to detect an invalid date. A regex is not enough.

function isValidDate(str) {
  // mm-dd-yyyy hh:mm:ss

  var regex = /(\d{1,2})[-\/](\d{1,2})[-\/](\d{4})\s*(\d{0,2}):?(\d{0,2}):?(\d{0,2})/,
    parts = regex.exec(str);

  if (parts) {
    var date = new Date(+parts[3], +parts[1] - 1, +parts[2], +parts[4], +parts[5], +parts[6]);
    if (date.getDate() == parts[2] && date.getMonth() == parts[1] - 1 && date.getFullYear() == parts[3]) {
      return date;
    }
  }

  return false;
}
Amit Agarwal

Amit Agarwal

Google Developer Expert, Google Cloud Champion

Amit Agarwal is a Google Developer Expert in Google Workspace and Google Apps Script. He holds an engineering degree in Computer Science (I.I.T.) and is the first professional blogger in India.

Amit has developed several popular Google add-ons including Mail Merge for Gmail and Document Studio. Read more on Lifehacker and YourStory

Awards & Titles

Digital Inspiration has won several awards since it's launch in 2004.

Google Developer Expert

Google Developer Expert

Google awarded us the Google Developer Expert award recogizing our work in Google Workspace.

ProductHunt Golden Kitty

ProductHunt Golden Kitty

Our Gmail tool won the Lifehack of the Year award at ProductHunt Golden Kitty Awards in 2017.

Microsoft MVP Alumni

Microsoft MVP Alumni

Microsoft awarded us the Most Valuable Professional (MVP) title for 5 years in a row.

Google Cloud Champion

Google Cloud Champion

Google awarded us the Champion Innovator title recognizing our technical skill and expertise.

Email Newsletter

Sign up for our email newsletter to stay up to date.

We will never send any spam emails. Promise.